At 12:29 PM 7/9/2006 +0200, you wrote:

>Vasile Surducan wrote:
> >
> > 2SD882 it's a real switching transistor with a 90Mhz bandwidth while 
> BD437 it's
> > a 3Mhz one.
>
>I thought 3Mhz would be plenty... Unfortunately I don't have a decent
>frequency counter around, but I'd hope it isn't trying to drive the CCFL
>at 10Mhz (how much RFI can that produce? This is supposed to be used
>inside PCs...)

No, a 3MHz ft is not plenty-- it's barely good enough for analog low-end
audio, like the ancient 2N3055.

ft is *unity gain* cutoff frequency, so a 3MHz ft transistor is pretty much
useless at 3Mhz, and would have low gain even with a 300kHz sine wave. The
blocking oscillator is probably operating at 50-100kHz. Change the transistor
to an appropriate type and it will work well again. The D882 is USD 0.74
from Digikey in quantity 1.

>Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com
->>Test equipment, parts OLED displys http://search.ebay.com/_W0QQsassZspeff


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